He photographed the most enduring images of the 60s folk-rock stars who lived in LA's Laurel Canyon. Now Henry Diltz stars in a documentary about the period. Sean O'Hagan looks back at Diltz's most iconic pictures

Philip French: A bracing documentary concerning the Iraq war, there's as much about the politically polarised audience (many walked out during Neil Young's provocative 'Let's Impeach the President' song) as about the performances